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Osmotic pressure on plant cells

Osmotic pressure on blood cells

Types of endocitosis

Enzymatic action

Diagram of the mitosis (I)

Diagram of the mitosis (II)

The mitosis under the light microscope

Fluorescent micrograph of the cell in metaphase

Human male karyotype

Codominance

Independent assortment and segregation of alleles in meiosis

Double-stranded DNA: the double helix (I)

Double-stranded DNA: the double helix (II)

DNA_ds base pairing (I)

DNA_ds base pairing (II)

Gene, DNA and chromosome

Single chromosome mutations

Two chromosome mutations

Genetic manipulation: making recombinant DNA (I)

Genetic manipulation: making recombinant DNA (II)

Genetic manipulation: making sticky ends

Animal cloning by nuclear transfer (I)

Animal cloning by nuclear transfer (II): Dolly the sheep

The voyage of the Beagle

Darwin's first evolutionary tree

Recombination by independent segregation of chromosomes in meiosis

Recombination by crossing over in meiosis (I)

Recombination by crossing over in meiosis (II)

Evolutionary change in the peppered moth

Natural selection of peppered moth for dark coloration

Natural selection of antibiotic-resistant bacteria

Types of speciation by cladogenesis

Speciation by geographic isolation: Darwin's finches

Caricature of Darwin as an ape

Intelligent Design

Why is the fossil record gappy and uneven?

Artistic depiction of the protoplanetary disk

Artistic depiction of the process of accretion in the protoplanetary disk

Acasta gneiss (I)

Acasta gneiss (II)

Earth's ice through geologic time

Earth's clock

Fossil stromatolites

Filamentous cyanobacteria

Depiction of Ediacaran life forms

Anatomy of trilobites

Cruziana, trackways of trilobites (I)

Cruziana, trackways of trilobites (II)

Reconstruction of an ammonite

Large ammonite fossil

Iridiscent ammonite fossil

The truth about dinosaurs

Fossil of Archaeopteryx (II) with impressions of feathers

Fossil of Archaeopteryx (III) with impressions of feathers

Replica of an Archaeopteryx skeleton

The crater of Chicxulub

Phylogenetic tree of Primates

Hominoids' skeletons

Phylogenetic tree of Hominines (I)

Phylogenetic tree of Hominines (II)

Phylogenetic tree of Hominines (III)

Pelvic girdle in hominines

Paranthropus boisei (I)

Paranthropus boisei (II)

Lucy (Australopithecus afarensis)

Reconstruction of the skull of Australopithecus afarensis

Turkana boy (Homo ergaster)

Incomplete skull of Homo antecessor from Atapuerca (Spain)

Archaic Homo sapiens (Cro-Magnon)

Comparison between H. sapiens and H. neanderthalensis skulls

Leaf anatomy

Cross section of a leaf (I)

Cross section of a leaf (III)

Stomata (I)

Stomata (III)

Stomata (IV)

Internal root anatomy

Cross section of a root

Internal stem anatomy

Vascular bundles of the stem

Xylem

Water movement in plants

Flowering spike of a meadow foxtail

Pine pollen grain

Types of buds

Trophic chains

Trophic web

Carbon cycle (I)

Carbon cycle (II)

Nitrogen cycle (I)

The flow of the Sun's radiation across the Earth (I)

The flow of the Sun's radiation across the Earth (II)

Variation of temperatures in the last 130 years

Records of monthly temperatures in the last 130 years

Variation of temperatures between 1979 and 2008

Main sources of CO₂ emissions

Annual greenhouse gas emissions by sector

Seasonal melting of the Greenland ice sheet

Measures to cool down the Earth

Worldwide consumption of CFCs and HCFCs

Causes and consequences of acid rain

Acid rain damaged wood

Acid rain damaged monument

The most dangerous species in the Mediterranean sea

Accumulation of DDT through the food chains

Land use before and after humans

Ecoregions status

Extinction hotspots

How would the Earth change if Mankind died off?

Earth's cutaway

Convection currents in the Asthenosphere

Prominent hotspots (I)

Prominent hotspots (II)

Heat flow in the Geosphere

The structure of a volcano

Mount Egmont volcano in New Zealand

Volcanic landscape in Saudi Arabia

Hawaii archipelago

Mons Olympus volcano in Mars

The Pacific Ring of Fire

Map of volcanoes

Map of earthquakes

Map of earthquakes epicenters in the past decades

Quakes in the Kuril-Kamchatka Trench

Types of seismic waves

Diagram of the formation of a tsunami

Water retreatment in the coast of Sri-Lanka before the tsunami

The opening of the Atlantic Ocean according to Antonio Snider-Pellegrini in 1858

Pangaea

Blank map of the tectonic plates

Earth's map showing the oceanic relief

Oceanic relief in the northern Pacific

The structure of a continental margin

Types of tectonic boundaries

Divergent tectonic boundary in Iceland

Convergent tectonic boundary between two continental plates

Convergent tectonic boundary between two continental plates: the Himalayas

Convergent tectonic boundary between an oceanic and a continental plate

Marianas trench

Bathyscaphe Trieste

Convergent tectonic boundary between an oceanic plate and a mixed plate

Transform boundary in the San Andreas fault

Peridotite

Diorite

Grey granite

Red granite

Syenite

Pegmatite

Porphyry

Andesite

Basalt

Pumice

Obsidiane

Phyllite

Micaceous schist

Banded gneiss

Augen gneiss

Marble

Quartzite

Sand dunes in the Arabian Empty Quarter

The formation of glacial ice from snow

West fjords in Iceland

Ice cap in Iceland

Tongue of the Malaspina Glacier in Alaska

U-shaped glacial valley

Cirque glacier (I)

The formation of a waterfall

Gorge and waterfalls

V-shaped river valley

Meanders

Meander in the river Duero, Spain

Meander in the river Meuse, France

Meanders in the river Cauto, Cuba

Dry river channel and alluvial fan in Iran

Ganges river delta

River Ebro delta

Coastal landforms

Breccia

Sandstone

Siltstone

Mudstone

Weathered limestone

Chalk

Flysch de Zumaia (III)